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How to Take Input From User in Java?

  • Difficulty Level : Basic
  • Last Updated : 19 Aug, 2021

Java brings various Streams with its I/O package that helps the user to perform all the input-output operations. These streams support all the types of objects, data-types, characters, files, etc to fully execute the I/O operations. There are two ways by which we can take input from the user or from a file

  • BufferedReader Class
  • Scanner Class

1. BufferedReader

It is a simple class that is used to read a sequence of characters. It has a simple function that reads a character another read which reads, an array of characters, and a readLine() function which reads a line.

InputStreamReader() is a function that converts the input stream of bytes into a stream of character so that it can be read as BufferedReader expects a stream of character.

BuffferedReader can throw checked Exceptions

Java






// Java Program For BufferedReader Class
import.java.io.*;
 
public class BufferedReader
   
{
   
  // Main Method
  public static void main(String [] args)
  {
    // Creating BufferedReader Object
    // InputStreamReader converts bytes to
    // stream of character
    BufferedReader BufferedReader_Name = new
      BufferedReader(new InputStreamReader(System.in));
                      
      // Asking for input from user
      System.out.println("Enter String : ");
      System.out.println("Enter Integer : ");
                      
      // String reading internally
      String String_name = BufferedReader_Name.readLine();
                 
      // Integer reading internally
      int Integer_value =
      Integer.parseInt(BufferedReader_name.readLine());
                      
      // Printing String
      System.out.println("Entered String : "+ String_name);
                      
      //Printing Integer              
      System.out.println("Entered Integer : "+ Integer_value); 
       
    }
                      
  }

Output : 

2. Scanner

It is an advanced version of BufferedReader which was added in later versions of Java. The scanner can read formatted input. It has different functions for different types of data types. 

  • The scanner is much easier to read as we don’t have to write throws as there is no exception thrown by it.
  • It was added in later versions of Java
  • It contains predefined functions to read an Integer, Character, and other data types as well.

Syntax for Scanner

Scanner Scanner_name = new Scanner(System.in);

Syntax for importing Scanner Class: To use the Scanner we need to import the Scanner Class

import java.util.Scanner ;  

Inbuilt Scanner functions are as follows

Hence, in the case of Integer and String in Scanner, we don’t require parsing as we did require in BufferedReader.

Java




// Java Program to show how to take
// input from user using Scanner Class
 
import java.util.Scanner;
 
class Scanner {
   
  public static void main( String[] args )
  {
     
    // Scanner definition
    Scanner Scanner_name= new Scanner(System.in);
     
    // input is a string read
    // by readLine() function
    String str= str.readLine();
     
    // print string
    System.out.ptintln("Entered String : "+ str);
     
    // input is an Integer
    // read by nextInt() function
    int x= Scanner_name.nextInt();
     
    // print integer
    System.out.ptintln("Entered Integer : "+ x);
     
    // input is a floatingValue
    // read by nextFloat() function
    float f = Scanner_name.nextFloat();
     
    // print floating value
    System.out.ptintln("Entered FloatValue : "+ f);
  }
}

 
 

Output :

 

Take user input in Java

Differences Between BufferedReader and Scanner

  • BufferedReader is a very basic way to read the input generally used to read the stream of characters. Its gives an edge over Scanner as it is faster than Scanner because Scanner does lots of post-processing for parsing the input; as seen in nextInt(), nextFloat()
  • BufferedReader is more flexible as we can specify the size of stream input to be read. (In general, it is there that BufferedReader reads lager input than Scanner)
  • These two factors come into play when we are reading larger input. In general, the Scanner Class serves the input.
  • BufferedReader is preferred as it is synchronized. While dealing with multiple threads it is preferred.
  • For decent input, easy readability. The Scanner is preferred over BufferedReader.

 

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